In spring 1943, radio broadcaster, naturalist, and nature writer Thomas Helm was cruising with his wife in a small sailboat off Florida's Gulf Coast. (Helm had been invalided out from the Navy after being severely wounded at Pearl Harbor). What he says he saw very clearly was a beast so odd he couldn't even suggest an identity. Helm was thoroughly familiar with seals, sea lions, and mustelids like otters: indeed, short of a degreed biological scientist, you couldn't have had a much better witness. A round head - like that of a tiger without visible ears - covered in chocolate brown fur and sitting atop a four-foot neck appeared in the water in front of him.. He had plenty of time for a good look, and altered course at one point to keep from coming too close (he originally saw it at 30-40 yeards, but does not say what his closest approach was.) Helm was insistent this was no known pinniped (seal or sea lion) - among other things, it had a relatively flat face with eyes looking forward, not on the sides, and this is what reminded him of a cat. Cryptozoologist Bernard Heuvelmans classified this as an example of his “Merhorse” type of sea serpent, although the head shape doesn't fit, while modern cryptozoologist Dale Drinnon writes it off as a normal pinniped. A pinniped, though, seems wrong to me. A seal or sea lion's head might give this appearance if the witnesses had had only a brief view straight on, but not when they had several minutes to watch it as they sailed by - they didn't see it from just one angle.
Helm's description and drawing of the face remind me a bit more of a manatee more than a pinniped, but it seems an impossible error to describe a nearly-neckless manatee as showing four feet of neck of smaller diameter than the head. There is no question this was a mammal - not only did it have fur, but definite whiskers. Helm thought the head was about the size of a basketball.
Helm insisted in his book Monsters of the Sea that, prior to the incident, he gave no thought to "sea serpents" of any kind. He asked local commercial fishermen if they'd seen anything like his animal, and they had not (though he noted almost all had their own tales to tell of odd sea creatures.) Neither they nor scientists he approached could tell him anything useful.
Well, there it is - and there it rests. We have a solid witness (accompanied by another adult) and a description not only impossible to reconcile with a known animal but with any of the "sea monster" sightings I can think of in which the head was described. Dr. Roy Mackal has suggested for some sea and lake monsters a kind of long-necked sirenian (a member of the group made up of the manatees and dugongs.) IF such an animal exists - and the evidence is scant - then Helm's animal could reasonably be placed in that category. As with so many cryptozoological sightings, this tale resides in a most unsatisfying limbo. It may be there forever.